The present invention relates to the operation of whirl-flow, fluidized bed type reactors. More particularly the invention relates to a method and equipment for operating whirling flow layer, fluidized bed reactors in a zero gravity environment and involving particularly space technology, whereby the reactor to be moved into outer space may be a bioreactor or the like and its weight is to be drastically reduced while the process material is to be treated gently as compared with terrestrially operated, fluidized bed reactors.
Whirling flow and fluidized bed reactors are known to be comprised of a gaseous-solid system. Such systems are known generally from the literature in a variety of ways. They are used e.g. for thermal treatment of materials such as drying, cooling, in cracking processes, during coal burning, in the cement making industry as well as in biotechnology. In all these cases a gas stream or a flow of a watery solution is run through the process material and at a speed that is basically amenable or capable of loosening the process material so that it hovers or floats in a gaseous/liquid flow during operation while being passed through by the gas. This speed in which the material can be loosened is a minimal speed involving a continuously flowing phase so as to attain and maintain floating and hovering conditions.
Bioreactors are usually operated in the submerged mode i.e. the process material hovers and floats in a watery solution on the basis of its specific weight. That method is disadvantaged as compared with a fluidized bed system using a gas, for the following reason. First of all a higher substrate concentration is possible in a fluidized bed, and the gas injection and introduction into such a bed is simpler; any removal of residual process heat and the removal of volatile products themselves is easier than in a liquid system. Bioreactions are being discussed for various applications in space technology and it should also be mentioned that the manufacture of certain pharmaceutical products as well as biological life maintaining systems are of great interest. In a broad sense efficiency, generally and in specific terms such as weight and weight savings and space occupation, are all very important aspects.
Certain unsolved problems exist in the operation of whirling flow layer and fluidized bed bioreactors when operated on Earth. They are very sensitive to shear forces and abrasion, particularly with biological material such as certain cell structures. In case of a whirling flow, and mixing and blending this mutual abrasion is not to be neglected. This of course is added to the gravitational forces that act on these parts. The reactions require a gas flow which is sufficiently large so as to compensate the friction and the effect of gravity. The forces which are arising under these conditions are too large for sensitive cells. In the case of operating such a reactor in outer space there is no gravitational acceleration which is an advantage. That is also a disadvantage for stabilizing fluidized bed conditions.